L3 - Pathology Terms Flashcards
better understanding of pathology terms and should be able to describe differences between similar entities - read previous lectures on : - Inflammation - Neoplasia - Cell adaptation
What is common between a cyst and an abscess
Both are cavities which are lined by tissue and condensed fluid
What is a cyst
A cavity which is lined by epithelium and filled with condensed fluid or secretions which vary depending on the type of epithelium lining.
When is the secretion in a cyst watery?
When the lining epithelium is serous e.g. The pleura that surrounds the lungs in the pleural cavity
When is the secretion in a cyst mucusy
if the lining epithelium is mucus-secreting columnar epithelium e.g. Goblet cells are found in the respiratory and gastrointestinal tracts
What is an abscess
a cavity lined by granulation tissue and pus made from dead or dying neutrophil leukocytes
What is a similarity between gruanulation tissue and a granuloma
they are both types of tissue that can form as part of the body’s response to injury or inflammation although they are 2 completely different lesions
What is granulation tissue
(pink tissue that grows over a wound during healing) a repair tissue that consists of newly formed blood vessels, myofibroblasts and immune cells
what is the puprose of the newly formed blood vessels and myofibroblasts in granulation tissue
- blood vessels bring in nutrients and oxygen for the repair process (and transport immune cells to fight infection and clear debris)
- Myofibroblasts bring in the collagen which creates the flexible matrix to support and strengthen the newly formed tissue
What are granulomas
a type of chronic inflammation characterised by an accumulation of modified macrophages ( epithelioid histiocytes) and other immune cells. It is a type 4 delayed hypersensitivity reaction and is commonly association with conditions like tuberculosis and sarcoidosis
what are epithelioid histiocytes
macrophages that have acquired an elongated, eputhelial like shape. They form tight clusters around the foreign substance (or irritant) walling them off to prevent spread.
what is the clinical appearance for granulomas
hard lumps (e.g. skin or lungs)
What is the process for granuloma formation caused by persistent TB
- macrophages present antigens via their MHC class II to CD4+ helper t cells
- Macrophages secrete IL_12 inducing the CD4+ helper cell to differentiate into Th1 subtypes which secrete IFN-y.
- IFN-y convert macrophages into epitheloid histiocytes and giant cells which get structured around a central core of necrotic cell debris ( where most of the bacteria is concentrated)
Apoptosis vs Necrosis
- Apoptosis is a form of programmed and controlled cell death
- Necrosis is uncontrolled cell death due to injury or disease
What is apoptosis
programmed cell death regulated by intracellular programms in which cells destined to die activate enzymes that degrade the cells’ own DNA and nuclear and cytoplasmic proteins
What are the key morphological features of apoptosis
- Cell shrinkage: The cell volume decreases and there is loss of specialised surface structures.
- Chromatin condensation: Nuclear chromatin condenses and aggregates peripherally under the nuclear membrane
- Formation of apoptotic bodies: The cell fragments into membrane-bound vesicles containing cellular organelles and nuclear material.
- Phagocytosis of apoptotic bodies: Apoptotic bodies are rapidly engulfed and cleared by phagocytes (primarily macrophages) WITHOUT triggering inflammation.
What is necrosis
the premature death of cells and living tissue caused by factors external to the cells or tissue e.g. infection toxins or trauma. It includes a spectrum of morphologic changes and is largely due to the progressive degradation of enzymes from the cell (lysosomes) or from leukocytes (neutrophils) that are recruited to the site of injury. this process evokes an acute inflammatory reaction and causes major disturbance of surrounding tissue
what are example subtypes of necorsis
- Coagulative necrosis - when blood flow is reduced/ stopped causing the cells to dry and become hard ( and white) e.g. heart, kidney and spleen and occurs
- Liquiefactive necrosis - (fat) cells dissolve and turn into a thick sticky liquid e.g. in the brain
- Suppurative necrosis - liquefactive necrosis with pus formation
- Caseus necrosis
- Fat necrosis - enzymatic destruction of fat tissue
- Gangrene
Plasia definition
suffix that means formation, growth, or proliferation
What is Hyperplasia
an increase in the number of cells in an organ or tissue.
What is neoplasia
abnormal and uncontrolled cell growth that is independent of normal regulatory mechanisms
Example of when hyperplasia vs neoplasia may occur
Hyperplasia happens in response to physiological demand e.g. Thyroid enlargement during pregnancy to meet increased thyroxine demand, but after pregnancy the thyroid will go back to normal .
Neoplasia happens when there are genetic mutations usually in oncogenes or tumour suppressor genes which result in the uncontrolled proliferation of cells e.g. thyroid tumour which wont regress
what controls hyperplasia
Hyperplasia is regulated by NEGATIVE FEEDBACK.
(It involves the increase in the number of cells which is under negative feedback control. As soon as the demand is withdrawn, the tissue or organ will go back to its normal size)
